Performa 630 won't power on

[kupouzar]

Hi all,
so I won a very likely new old stock Performa 630 on eBay. I think it is basically new since there's literally no dust inside and the case is still white. There's also no leakage anywhere. However, it doesn't power on.
The PSU is most likely working since I even measured very stable 5V trickle voltage. I tried replacing the 4,5 Rayovac battery but still no dice. Do you have any ideas? So far I've ordered some tantalum caps for the LB which I'm going to replace this evening.

 

[Phipli]

Hi all,
so I won a very likely new old stock Performa 630 on eBay. I think it is basically new since there's literally no dust inside and the case is still white. There's also no leakage anywhere. However, it doesn't power on.
The PSU is most likely working since I even measured very stable 5V trickle voltage. I tried replacing the 4,5 Rayovac battery but still no dice. Do you have any ideas? So far I've ordered some tantalum caps for the LB which I'm going to replace this evening.

Hum. I'd generally suspect the PSU. Perhaps despite the trickle voltage.

Are you absolutely sure there is no leakage? The SCSI circuit was damaged on one of mine, at the vias near the battery.

Have you tried the power button on the back as well as a keyboard?

Does the PSU make any sounds when you press the power button?

Have you tried shorting the power on pin on the psu to see if the PSU turns on at all?

 

[kupouzar]

The boards are absolutely pristine, I even inspected them closely and against light. I do own another working 630 though so I'll try a board swap. I don't have it currently at my place though, neither do I have a keyboard so I just tried pressing the push button on the machine.
PSU makes a slight whine only when I unplug the AC cable which I suppose is completely normal. Which one of those pins is the PS_ON signal? I couldn't find it anywhere online.

 

[kupouzar]

Hum. I'd generally suspect the PSU. Perhaps despite the trickle voltage.

Are you absolutely sure there is no leakage? The SCSI circuit was damaged on one of mine, at the vias near the battery.

Have you tried the power button on the back as well as a keyboard?

Does the PSU make any sounds when you press the power button?

Have you tried shorting the power on pin on the psu to see if the PSU turns on at all?

I've just found the pinout. I'll try to short it to the ground when I get back home.

 

[kupouzar]

Okay, so it's indeed a fault of the PSU. And I've also found out that it has previously been tampered with the board unfortunately. Someone cut a resistor off and replaced a diode with a weird combination of two. Tried recapping the PSU but that didn't work out either so my plan is to buy a cheap Fortron SFX PSU and rebuild the PSU using this awesome guide.
Btw, the rear power button definitely works since if I press it, the trickle voltage appears on the PS_ON pin for like 3s. Nothing more happens and it disappears again. As there are no schematics for this Astec PSU available, I don't want to poke around with it anymore.

 

[pizzigri]

I did as you intend to do - made a new PSU from an SFX box for my 6200 with 6500 board and never looked back.

 

[kupouzar]

So I did it and it works perfectly. As always, thanks for your help!